1. Field of the Invention
The present invention relates to a tumor marker for diagnosis of cancer, especially for diagnosis of ovarian cancer, which can be applied in early diagnosis of ovarian cancer.
2. The Prior Arts
Human ovarian cancer is one of the common gynecological malignancies. In the developed country, it is one of the leading causes of death of the gynecological cancers, and the five-year survival rate is only about 30%. Overall about one woman in 70 will get ovarian cancer, and estimated one woman in 100 will die from this cancer in USA. This is because the illness is often diagnosed during late stage of the cancer. The cancer has often spread beyond the ovaries at that time, and therefore related to the low survival rate. Though Taiwanese women do not have a high incidence of ovarian cancer, but the incidence has increased over past two decades.
The five-year survival rate will up to 90-95 percent if the ovarian cancer is caught very early according to previous medical reports. The lack of reliable tumor marker has made the early detection of ovarian cancer difficult. Therefore most of the ovarian cancer patients will be diagnosed when the cancer cells have been spread. The survival rate thus cannot be lowered.
CA-125, cancer antigen-125, is a protein that may be released into the bloodstream, and is found at levels in most ovarian cancer cells. It is also a serum marker being studied thoroughly. The known detection method for ovarian cancer is the measurement of CA-125 in serum to assess the risk of having ovarian cancer.
The CA-125 test only returns a true positive result for about 50% of Stage I ovarian cancer patients though it has an 80% chance of returning true positive results from stage II, III, and IV ovarian cancer patients. It yields many false positive results. Therefore it is not recommended as a diagnostic tool or target for ovarian cancer in early stage cancers. Due to the current limitation to early diagnosis of ovarian cancer, it is important to search and identify new potential biomarkers in ovarian cancer.